SOOW Cable for VFD Controlled Motor 1

[Kingstonrupp]

Hello,

I am dealing with an expansion to an existing facility where VFD controlled motors in a washdown area have been fed powered with SOOW cables from JBs mounted at ceiling level. The service and motors are 600vac. We were planning to replicate the existing installations, but I am concerned that the SOOW cable being rated at 600Vac may not be adequate for dealing with voltage spikes or reflected waves. Would Type W cable be a better choice since it is rated at 2000Vac? VFD specific cable are likely not going to be a favorable choice to the client because of cost. Any experience on this type of install would be appreciated.

Thanks

 

[itsmoked]

How far from the VFDs to motors?

Conduit from VFDs to JBs?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[jraef]

With no shielding, what is the cost of down time due to the EMI/RFI bleeding off of that relatively powerful radio transmitter you are creating and interfering with or degrading your local electronics?

I once had Army scientists (and MPs) in Nevada converge on me from 20+ miles away by triangulating on the radio signal off of my 5HP motor connected to a VFD with SO cord.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

 

[Kingstonrupp]

There are a variety of motors with various distances. Closest motor is probably 10 meters and everything goes up from there. No conduits being used.

 

[jraef]

That's fine, but the argument that they can't afford the shielded flexible cable is spurious. That's what it is for and to ignore the risks is not prudent.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

 

[Kingstonrupp]

Agree, and I intend to make them aware of the risks. From their point of view though, if the previous installations have been providing what is required without issue, they do not see a point in spending more $. Tough to argue.

I have been involved in many projects for Oil and Gas facilities where Teck cable is used to power the VFDs, but no specific purpose VFD cables. As far as I am aware the facilities seem to operate fine without. Is the aluminum armour around the conductors considered an adequate shield even though it is not continuous? Also, we always specify 1kV teck instead of 600V for VFD motors. Some people have told me this is overkill and 600V will work fine. Supply service is always 480V FYI....

 

[GroovyGuy]

Howdy Kingston,
I have installed hundreds of PWM type 6-pulse VFDs throughout my career and in 99% of those installations have used 3-conductor TECK cable, with no issues. I know that some cable OEMS do offer a specialty drive cable, but I have never used it.
Having said that, I have always used a dv/dt filter on the drive output; this helps a lot with longer feeder lengths as well as the noise issue (at least in the higher harmonics).

As far as 600V vs 1000V insulation, any cost difference is minimal. This application does not warrant a 2kV solution. FYI: I have noticed that cable OEMS only make 1000V rated TECK cable in sizes > 8awg. For sizes 8awg and smaller you don't have a choice; only 600V rated cable is available.

Unless the flexibility of a type SOW cable is required, a would stick with TECK type cables. I can only guess that the armour does provide shielding (at least for the higher frequencies).
GG


"I have not failed. I've just found 10,000 ways that won't work." Thomas Alva Edison (1847-1931)

 

[waross]

Try Nexans for 1000 Volt rated Teck in sizes down to #14

http://www.nexans.ca/eservice/Canad...REX_II_TECK90_XLPE_1_kV_3C_.html#doc_and_info

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[GroovyGuy]

Hi Bill,

I know that some cable OEMs have 1000V TECK, for small sizes, listed in their catalogs, but have you ever tried to buy it? In my experience, 1000V (small TECK) is not stocked by cable suppliers.

I also understand that 1000V armoured power cable (ie TECK) is a marketing ploy by Canadian manufacturers in an effort to differentiate TECK cable from cheaper US Metal-Clad (MC) cables. [ Note: I realize that MC cable does not have the inner PVC jacket, as does TECK. In my opinion, this is a big deal. ]
GG

"I have not failed. I've just found 10,000 ways that won't work." Thomas Alva Edison (1847-1931)

 

[waross]

I see a lot of 1000 Volt Teck in the smaller sizes on job sites in the oil patch. Also see a lot of 600 Volt Tech. It almost seems random.
I was on a project many ears ago when ACWU-90 cable was spec'ed instead of Teck.
That is Armoured Cable Wet Underground. Basically the old BX with a jacket.
Then the fun started. The connectors were ordered by Teck cable sizes. None would fit. For a given configuration the cable diameter was less.
Connectors were re-ordered based on the overall diameter. Some fit but most did not have a large enough throat for the conductors.
On the third order of connectors the purchasers got it mostly correct.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jraef]

... if the previous installations have been providing what is required without issue, they do not see a point in spending more $. Tough to argue.

Here's the thing. Do they KNOW that there have been no issues? The "issues' would not be with the VFDs or the motors, they would be with OTHER surrounding equipment that may or may not be receiving spurious data or service interruption or component degradation as a result of the RFI from those cables bleeding all over everything nearby. I was called out to a site once because no matter what, the OEM could not get an brand of digital pressure transmitter to last more than a few weeks without starting to go completely haywire and spit out garbage. I was helping them out with a particular brand of transmitter that had a very good reputation (Sick), but it too died in a matter of weeks. When I got there to take a look at it, he had 6 small VFDs all connected to the motors with SO cord. I turned off the VFDs, the signals from the transmitter stabilized. Turned them on one by one, the signal got worse and worse. Why did it last a few weeks? My theory was that it had some amount of protection against this built-in, but the constant bombardment of the RFI from the drives eventually burned that out, leaving the sensor unprotected. Changed the output wiring to shielded VFD flex cable and it all went away and never came back. Ultimately, they spent many times more money chasing ghosts in replacing that sensor and wiring they would have spent on just using the slightly more expensive cable to start with.

http://www.belden.com/products/industrialcable/high-flex-vfd-cable.cfm

http://lappusa.lappgroup.com/motors-drives-cable.html

http://www.amercable.com/doc/catalogs/industrial/industrialvfd.pdf

"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington